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Zinc phosphide (Zn3P2) has been lauded as a promising solar absorber material due to its functional properties and the abundance of zinc and phosphorous. In the last 4 decades, there has not been any significant improvement in the efficiencies of Zn3P2-based solar cells. This is vastly due to the limited understanding of how to tune its optoelectronic properties. Recently, significant progress has been made in the growth and charac-terization of the material, which has shed light on its potential. In this study, we report an energy conversion efficiency as high as 4.4% for a solar cell based on a polycrystalline Zn3P2/InP heterojunction. This device presents an open circuit voltage of 528.8 mV, 7.5% higher than the Zn3P2 homojunction record. We investigate the dominant recombination mechanisms within the film using different techniques to identify the key factors underpinning our device efficiency. In particular, we pinpoint that reduced carrier collection at the front of Zn3P2 is responsible for the reduced collection of high-energy photons. This allows us to suggest the design rules for next-generation Zn3P2-based heterojunction solar cells, which should allow us to go beyond the current con-version values.

A novel multiscale technique called the Bridging Cell Method (BCM) was used to model the mechanical behavior of Nextel 720 composite fibers across a range of temperatures. The previously validated room temperature Nextel BCM was used as a benchmark, and a temperature-dependent formulation was employed to account for the temperature effect. The model was tested under uniaxial tensile loads ranging from room temperature to 1700 K. The results were evaluated in terms of ultimate tensile strength (UTS), elasticity, and failure strain. The temperature-dependent Nextel BCM was validated via experimental data obtained from the literature. The high-temperature drop in composite's strength was predicted by the Nextel BCM. This was the result of implementing the fibers' microstructural evolution into the model, caused by phase transformation occurring at higher temperatures. The model was further validated with the fracture resistance variations of the composite that resulted from changes in crack length. The fracture behavior of the fibers at room and high temperatures were tested, by applying inter- and intra-granular cracks. Finally, the effect of grain alignment with respect to the applied load was investigated. The results show that the Nextel BCM is capable of predicting Nextel 720 composite's mechanical behavior across a range of temperatures.

The mechanical behavior of Nextel 720 ceramic matrix composite fibers was modeled using a novel multiscale modeling technique called the Bridging Cell Method (BCM). The BCM divides the system into three domains: atomistic, bridging, and continuum; with seamless coupling between the atomistic and continuum domains. The BCM allows considering the effects of the nano- and micro-structural characteristics of the material when modeling a macro-scale bulk. It incorporates interatomic potentials and quasi-harmonic calculations to find the final state of the system. The mechanical properties of the as-received fibers were investigated in tension via microtesile testing. The experimental results – evaluated in terms of the ultimate tensile strength , failure strain, and elasticity of the fibers under uniaxial loads – stood within the range reported in the literature; these results were then used to validate the Nextel BCM model. The Nextel BCM was conducted in two steps. First, the atomistic structure was relaxed. Then, a nano-crack was introduced in the mullite/alumina interface and the structure was pulled under a uniaxial tensile load until failure occurred. The BCM results indicated a good match between the Nextel BCM model and the experimental results. The validated Nextel BCM model can be used for the structural analysis of fibers.

The Darrieus vertical axis wind turbine (VAWT) has been the subject of a large number of recent studies to improve self-starting capability and aerodynamic performance. This study presents a computational fluid dynamics simulation of the vertical axis wind turbine with fixed and variable pitch at different solidities. In order to introduce the best efficiency value of solidity for a variable-pitch vertical axis wind turbine, a computational modeling of two-dimensional transient flow around a VAWT at solidities between 0.2 and 0.8 and turbine with two, three and four blades is conducted. The numerical simulation models the flow field around a turbine rotor by solving the strong nonlinearity of URANS and SST k-ω turbulence model, utilizing the semi-empirical numerical model. To simulate the turbine in a variable pitch method, the user-defined function (UDF) code and the moving mesh method are used. The results show that variable pitch blades with high solidities are preferred when the initial self-starting torque is required. Moreover, the variable pitch blades are capable to produce more torque at high solidities. Therefore, the vortex interaction between upwind vortices and blades in downwind stream is decreased. The results verify that the power reduction of fixed pitch VAWT at high solidities could be solved by utilizing the variable pitch technique.

This paper discusses the novel design of VAWT by employing porous media on turbine blades. 2D simulation was performed with CFD package Star CCM to observe flow behavior around VAWT blades. DU 06-W-200 airfoil with six porous configurations including both the pressure and suction side of airfoil have been investigated to obtain optimum porous location. The aerodynamic coefficients of these configurations have been calculated and compared with that of the conventional blade for the broad range of angle of attack. It is found that porous media on the pressure side of airfoil behave more effectively and increase the C L / C D values. Then three straight blade Darrieus type rotor performance in presence of porous media has been studied. The results reveal the enhancement of power and torque coefficient in a range including both before and after optimum tip speed ratio. Therefore, the turbine self-starting capability improves and consequently, it starts operating at low wind speed which leads to the reduction of VAWT cut-in and increases annual energy production. Additionally, the blade equipped with porous media experience a higher stall angle of attack and is able to exceed the maximum azimuth angle of the conventional rotor. Hence, stall phenomena delay and occurs at a higher angle of attack. The main reason for these improvements is related to the capability of porous media to attach the flow on blade profile and suppress separation zone.

This study applied a novel Bridging Cell Method (BCM) multiscale modeling technique to identify the internal energy and lattice parameter variations of mullite with respect to the oxygen vacancy content of its structure, at temperatures ranging from 300 K to 1500 K. The BCM model decomposed the system into three domains: continuum, bridging, and atomistic. Temperature-dependent numerical calculations were then applied to solve the systems of equations. Next, the supercells of mullite were generated by removing oxygen atoms from a silimanite crystal structure and replacing the Si with Al atoms. Such replacements occurred in the atomistic domain where interatomic and temperature-dependent potential functions were used to obtain the internal energy and lattice parameter variations of the mullite family as a function of the structure’s temperature and oxygen vacancy. The results were validated at different temperatures via applicable experimental data previously reported in the literature. At all temperatures, the results indicate a linear relationship between the internal energy/cell of mullite and the oxygen vacancy factor. Lattice parameter a was found to linearly increase as the oxygen vacancy increased, whereas the b and c lattice parameters nonlinearly reduced or increased, respectively. Furthermore, in all cases, a temperature elevation led to a linear increase in the lattice parameter since the thermal expansion coefficient was found to be positive in all three directions. The results indicated that the main origin of lattice parameter fluctuations in the mullite family is the rotation of the structure around the c-axis, which is attributable to the removed oxygen atoms hence, there is a longer bond length of Al–O as compared to Si–O. Additionally, the thermal properties of mullite including variations in the internal energy and lattice parameter fluctuations with respect to temperature, are independent of the composition. This validated BCM mullite model can be used for structural analysis at higher temperatures.

In this paper, the modified two-component non-homogeneous mixture model of Buongiorno is developed for the case of forced convection of alumina–water non-homogeneous nanofluid flow in concentric micro-annular tubes at constant wall temperature (CWT). Two different thermal boundary conditions have been considered such that for Case A the inner wall is adiabatic and the outer wall is kept at a constant temperature while for Case B the inner wall temperature remains constant and the outer wall is thermally isolated. Assuming a hydrodynamically and thermally fully developed flow, the governing equations of nanofluids in a concentric annulus are reduced to a nonlinear system of ordinary differential equations and solved using an appropriate reciprocal numerical algorithm via Runge–Kutta–Fehlberg method. The effects of N B T (from 0.7 to 10), ϕ B (from 0.01 to 0.03), λ (from 0.05 to 0.2) and ζ (0.4, 0.5 and 0.6) on the non-dimensional volume fraction of nanoparticles, velocity, and temperature profiles have been investigated for both cases. It is indicated that the anomalous heat transfer enhancement depends on the thermal boundary condition as well as the ratio of thermophoresis and Brownian motion. Furthermore, for Case B, there is an optimum nanoparticle diameter around 0.5 N B T 1 that the thermal performance reaches its peak. However, for Case A, the thermal performance increases as the nanoparticle diameter increases. For both cases, the thermal performance decreases with an increase in the nanoparticle concentration.

Laminar fully developed mixed convection of magnetohydrodynamic nanofluids inside microtubes at a constant wall temperature (CWT) under the effects of a variable directional magnetic field is investigated numerically. Nanoparticles are assumed to have slip velocities relative to the base fluid owing to thermophoretic diffusion (temperature gradient driven force) and Brownian diffusion (concentration gradient driven force). The no-slip boundary condition is avoided at the fluid-solid mixture to assess the non-equilibrium region at the fluid-solid interface. A scale analysis is performed to estimate the relative significance of the pertaining parameters that should be included in the governing equations. After the effects of pertinent parameters on the pressure loss and heat transfer enhancement were considered, the figure of merit (FoM) is employed to evaluate and optimize the thermal performance of heat exchange equipment. The results indicate the optimum thermal performance is obtained when the thermophoresis overwhelms the Brownian diffusion, which is for larger nanoparticles. This enhancement boosts when the buoyancy force increases. In addition, increasing the magnetic field strength and slippage at the fluid-solid interface enhances the thermal performance.

In this paper, the laminar fully developed flow of alumina/water nanofluid inside circular microchannels subjected to a constant wall temperature (CWT) is theoretically investigated. The effect of nanoparticles migration originating from thermophoretic diffusion (temperature-gradient driven force) and Brownian diffusion (concentration-gradient driven force) on the thermophysical characteristics of nanofluids has been considered. A Navier's slip condition is considered at the wall to model the non-equilibrium region at the fluid-solid interface. In order to assume a hydrodynamically and thermally fully developed flow, the governing equations are reduced to a system of ordinary differential equation and solved using the appropriate reciprocal algorithm. The effects of pertinent parameters including the ratio of Brownian motion to thermophoresis ( N BT ), slip parameter ( λ ) and bulk mean nanoparticle volume fraction ( ϕ B ) on the flow and thermal fields are investigated. In addition, the results are compared with the case of constant heat flux (CHF) at the wall. The figure of merit ( FoM ) is used to measure the thermal performance of equipment and finding the optimum thermal condition. It is shown that the anomalous heat transfer enhancement depends on the thermal boundary condition as well as the nanoparticles diameter. Furthermore, the optimum value of N BT for the case of constant wall temperature (approximately 1) is found to be greater than that of the constant wall heat flux (approximately 0.5). Thus, it can be concluded that the optimum diameter of nanoparticles for the case of constant wall temperature should be smaller than that of constant wall heat flux.

The present research aims to investigate the concept of J-shaped blade in a straight–bladed Darrieus type VAWT in terms of output torque and power by employing high-fidelity 3D numerical simulations. Theoretically, since the J-shaped blades can benefit from the lift and drag forces simultaneously, this combined forces help the turbine possess faster operation at low wind speeds, thereby resulting in the termination of self-starting problem and improving power coefficients, especially at low and moderate tip speed ratios. In this study, NACA0015 is served as the base airfoil and has been modified to generate the desired J-shape profile. The attained results indicate improvements on torque and power coefficients, more specifically in the first half of revolution namely 0°

Objective To examine the severity of cough and straining at the time of emergence from anesthesia. Design Double-blind randomized, placebo-controlled study. Setting University-affiliated hospital. Patients Sixty-two American Society of Anesthesiologists 2 patients undergoing craniotomy and excision of supratentorial cerebral tumors. Intervention Intravenous infusion of remifentanil (REM) at 0.05 μg/kg/min or normal saline (NS) upon termination of the surgical procedure. Measurements Heart rate (HR) and mean arterial pressure (MAP) along with the frequency and severity of cough response (Modified Minogue Scale) to the endotracheal tube were recorded at different time points. The frequency of cough and straining was analyzed with χ 2 tests. HRs and MAP were analyzed by repeated-measures analysis of variance between REM and NS groups. Main Results There was no case of significant cough in the REM group, and all of the patients in the NS group developed some extent of cough varying from mild retching to severe coughing episodes ( P Conclusion Infusion of REM at the end of craniotomy procedures results in significant reduction of the frequency and severity of coughing and straining. Compared to placebo, REM moderates increases in MAP upon emergence from general anesthesia until the time of extubation.

In this study a 3 kW straight–bladed Darrieus type Vertical Axis Wind Turbine (VAWT) is investigated numerically using OpenFOAM computational fluid dynamic package. The newly proposed J-Shaped profile is used as the blade airfoil in the simulation. The J-Shaped profile is designed by means of eliminating a fraction of pressure side of Du 06-W-200 airfoil. The main purpose of this investigation is the improvement of the VAWT starting torque using J-shaped profile. The power curves for both conventional and J-shaped profiles are calculated and the torque variation is obtained at different azimuth angles. In addition, the vorticity and pressure field surrounding the wind turbine is presented. The results indicate that the performance of turbine is optimized for J-shaped profile which eliminates the pressure side of airfoil from the maximum thickness toward the trailing edge. Moreover, by employing this J-Shaped profile, the wind turbine performance is intensified TSRs and self-starting of turbine is improved.

Purpose The aim of this systematic review was to evaluate the effectiveness and safety of dexmedetomidine used for sedation of patients with sepsis. Methods We searched Medline, Scopus, TRIP and CENTRAL, DART, OpenGrey, and ProQuest without applying any language filter up to July 15, 2015. Two of the authors independently reviewed search results for irrelevant and duplicate studies and extracted data and assessed methodological quality of the studies. We used tabulation to synthesize the findings of the studies and transformed data into a common rubric and calculated a weighted treatment effect across studies using Review Manager. Results We found 124 references in 7 databases, and after exclusion of irrelevant and duplicate studies, 6 studies with total number of 242 patients with sepsis were included. The risk ratio for 28-day mortality was 0.49 (95% confidence interval, 0.24-0.99; P = .05) for the dexmedetomidine group vs the control group. The weighted mean difference for the length of stay in the intensive care unit was 1.54 (95% confidence interval, −1.73 to 4.81; P = .36). No adverse effect including hypertensive, hypotensive, or bradycardia response was reported in any studies. Conclusion In a small group of studies of patients with sepsis, dexmedetomidine improved short-term mortality compared with other sedatives without affecting the intensive care unit length of stay. Further studies are warranted to confirm whether using this particular agent improves sepsis outcomes in comparison to other commonly used sedating agents.

Molecular dynamics was applied to develop a novel PDMS and PDMS-Ni nanocomposite model. First, the PDMS model was validated in terms of the elastic and compressive moduli using available experimental data. The model was then used as a benchmark to add Ni nanoparticles and create a PDMS-Ni conductive nanocomposite model. This model was studied under uniaxial tensile and compressive loading conditions for different Ni filler ratios and mean particle diameters. The electrical resistivity of the model was then obtained as a function of pressure and the compressive stresses. The PDMS-Ni MD model was validated via the literature and shown to successfully predict electrical resistivity variations versus compressive stresses. The results show that as the Ni filler ratio increased from 3:1 to 6:1, the drop in initial electrical resistivity of the composites occurred much faster and at lower stresses. Furthermore, as the mean Ni particle diameter size was increased from 1 nm to 5 nm, the electrical conductivity of the PDMS-Ni improved at different filler ratios. The developed PDMS-Ni MD model can be used to study the electrical and mechanical behaviors of such materials in biosensor applications. It can further be used to study the effects of adding other fillers to PDMS matrix.

Thermodynamic phase diagrams are the cornerstones to develop synthesis of new materials. Zinc phosphide has evolved into a prospective semiconductor for next generation solar cells, thanks to its abundance and functional properties. Here we derive an optimized Zn-P binary diagram, and compare it to two previously available assessments. We solve some of the artefacts and clarify the methodology to obtain the Gibbs free energy, reaching an accurate description of the phases. This work is important for the synthesis of zinc-phosphide in the form of thin film and nanostructures.

In this study, free vibration analysis of moderately thick symmetrically laminated general trapezoidal plates with various combinations of boundary conditions is investigated. The governing partial differential equations and boundary conditions for trapezoidal plate are obtained using first order shear deformation theory (FSDT) together with proper transformation from Cartesian system into trapezoidal coordinates. Generalized differential quadrature (GDQ) method is then employed to obtain solutions for the governing equations. Results of the GDQ method are compared and validated with available results in the literature which show accuracy and fast rate of convergence of the method. Effect of various parameters such as geometry, thickness, boundary condition and lay-up configuration on the natural frequency of trapezoidal and skew plates is investigated through several examples. It is also shown that the method can be used for analysis of triangular plates as special case of trapezoidal geometry with the same performance and convergence.

We have evaluated the role of the HLA-DRB1*1501 allele and the IL-2 -330 T/G polymorphism and their interaction in susceptibility to multiple sclerosis on 360 patients and 426 matched healthy individuals. We used the SSP-PCR method to determine the alleles. Fisher's exact test was used to analyses. We observed a significant increase in the T allele at IL-2 -330 position in patients (OR=1.34, P

Background Cystic fibrosis (CF) is the most common inherited disorder in Caucasian populations, with over 1400 mutations identified in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. Mutations in the CFTR gene may be also causative for CBAVD (Congenital Bilateral Absence of the Vas Deferens). The type and distribution of mutations varies widely between different countries and/or ethnic groups, and is relatively unknown in Iran. We therefore performed a comprehensive analysis of the CFTR gene in Iranian CF patients. Methods 69 Iranian CF patients, and 1 CBAVD patient, were analysed for mutations in the complete coding region, and its exon/intron junctions, of their CFTR genes, using different methods, such as ARMS (amplification refractory mutation system)-PCR, SSCP (single stranded conformation polymorphism) analysis, restriction enzyme digestion analysis, direct sequencing, and MLPA (Multiplex Ligation-mediated Probe Amplification). Results CFTR mutation analysis revealed the identification of 37 mutations in 69 Iranian CF patients. Overall, 81.9% (113/138) CFTR genes derived from Iranian CF patients could be characterized for a disease-causing mutation. The CBAVD patient was found to be homozygous for the p.W1145R mutation. The most common mutations were p.F508del (ΔF508) (18.1%), c.2183_2184delAAinsG (2183AA>G) (6.5%), p.S466X (5.8%), p.N1303K (4.3%), c.2789+5G>A (4.3%), p.G542X (3.6%), c.3120+1G>A (3.6%), p.R334W (2.9%) and c.3130delA (2.9%). These 9 types of mutant CFTR genes totaled for 52% of all CFTR genes derived from the 69 Iranian CF patients. Eight mutations, c.406-8T>C, p.A566D, c.2576delA, c.2752-1_2756delGGTGGCinsTTG, p.T1036I, p.W1145R, c.3850-24G>A, c.1342-?_1524+?del, were found for the first time in this study. Conclusions We identified 37 CFTR mutations in 69 well characterized Iranian CF patients, obtaining a CFTR mutation detection rate of 81.9%, the highest detection rate obtained in the Iranian population so far. These findings will assist in genetic counseling, prenatal diagnosis and future screening of CF in Iran.